Screening methodology for bank erosion estimation at pipeline watercourse crossings

A screening level model was developed to estimate bank erosion at pipeline watercourse crossings to provide estimates of the probability of pipeline exposure resulting from various extreme flood events. The model uses estimates of flood duration and maximum water velocity during flooding to predict the amount of bank erosion that would occur and compares the results to the horizontal “setback” distance. When the predicted horizontal erosion is equal to horizontal distance between the pipeline and the bank position, the probability of that flood occurring is equal to the probability of pipeline exposure due to bank erosion. The results of the bank erosion calculation can then be compared to: the probability of the flood causing exposure by scour and/or avulsion; regulatory acceptance criteria for pipelines; and company integrity objectives to assess the need for additional investigation or proactive mitigation.